E919 - Nitrosyl chloride

At a glance

• What it is: A yellow, highly reactive gas (chemical formula NOCl) with a sharp, irritating smell.
• Food role: Intended as a flour treatment/bleaching agent to modify flour and dough properties.
• Where it’s found: Not authorized as a food additive in the European Union; unlikely to appear on modern retail labels.
• Safety: Corrosive, toxic by inhalation, and irritating to eyes and lungs; handled only with industrial safeguards.
• Common substitutes: Other flour improvers such as ascorbic acid, L-cysteine, enzymes like alpha-amylase, and, in some jurisdictions, agents like chlorine dioxide or benzoyl peroxide.

Why is Nitrosyl chloride added to food?

When it has been considered for food use, nitrosyl chloride’s role is as a flour treatment and bleaching agent. Flour treatment agents are added to improve dough handling and baking performance, while bleaching agents are used to whiten or decolorize foods through chemical reactions.¹ In principle, such agents can speed up flour maturation and influence dough strength and loaf volume, which is why millers and bakers rely on this functional class (using permitted substances) rather than extended flour aging.¹

What foods contain Nitrosyl chloride?

Under the European Union’s “Union list” of permitted food additives, E-numbers identify additives that are authorized for specific uses. Nitrosyl chloride (E919) is not on the current Union list, so foods marketed in the EU should not contain it as an additive.² Where flour bleaching gases are permitted in other jurisdictions, usage is typically limited to flour milling or baking environments and not common in finished, packaged foods.

What can replace Nitrosyl chloride?

Bakers and millers have many established alternatives, chosen according to local regulations and desired effects:

• Oxidizing and dough-strengthening agents: ascorbic acid³
• Reducing agents for dough extensibility: L-cysteine
• Enzyme systems for dough performance: alpha-amylase
• Bleaching/oxidizing agents where allowed: chlorine dioxide, chlorine, benzoyl peroxide, or ammonium persulfate
• Legacy or jurisdiction-specific improvers: azodicarbonamide, potassium bromate

Always check your market’s rules, as permissions differ widely.

How is Nitrosyl chloride made?

Industrially, nitrosyl chloride is commonly produced by reacting nitric oxide (NO) with chlorine (Cl2). It is a yellow to reddish gas at room temperature and decomposes to other nitrogen oxides and chlorine under certain conditions.⁴

Is Nitrosyl chloride safe to eat?

Nitrosyl chloride is not intended for direct consumer exposure. It is a corrosive, toxic gas that can severely irritate or damage the respiratory tract and eyes on inhalation or contact, requiring strict industrial controls.⁴ As a food additive, it is not on the European Union’s list of authorized substances, so it cannot be used in EU foods.² Other jurisdictions set their own rules, but given the material’s hazards, food-grade use—if permitted at all—is tightly restricted to controlled processes.

Does Nitrosyl chloride have any benefits?

In theory, its benefits are the general benefits of flour treatment and bleaching agents: faster flour “maturation,” whiter flour color, and adjustments to dough handling and loaf volume.¹ In practice, modern flour technology achieves these effects with other authorized agents, notably ascorbic acid, which EFSA, the European Food Safety Authority, recognizes as a dough improver in the EU.³

Who should avoid Nitrosyl chloride?

• Consumers are not expected to encounter nitrosyl chloride directly in foods in the EU, where it is not authorized.²
• Workers could be exposed in industrial settings; without proper controls, inhalation is dangerous due to its corrosive, irritating properties.⁴ People with respiratory conditions (such as asthma) are especially vulnerable to irritant gases and should not be exposed.

Myths & facts

• Myth: “E-numbered additives are all currently permitted in the EU.”
  Fact: E-numbers are identifiers used in Europe, but only additives on the current Union list are authorized; E919 is not on that list.²
• Myth: “This is the gas used to cure meats.”
  Fact: Meat curing relies on nitrate/nitrite systems that generate nitric oxide in meat; nitrosyl chloride is not a curing agent approved for that purpose.⁵
• Myth: “If it’s a gas, it can’t affect food.”
  Fact: Several approved food additives are gases; they can function as processing aids or additives that change food or ingredient properties during manufacture.¹

Nitrosyl chloride in branded foods

You are unlikely to see E919 on ingredient labels in the EU, where it is not authorized as a food additive.² When flour treatment involves gases in jurisdictions that allow them, it typically occurs at the milling or baking stage under controlled conditions rather than appearing as a retail ingredient claim.

References

Footnotes

1. Food additive functional classes and definitions (GSFA Online) — FAO/WHO Codex Alimentarius. https://www.fao.org/gsfaonline/functional-classes.html ↩ ↩² ↩³ ↩⁴

2. Commission Regulation (EU) No 1129/2011 establishing the Union list of food additives — eur-lex.europa.eu. https://eur-lex.europa.eu/eli/reg/2011/1129/oj ↩ ↩² ↩³ ↩⁴ ↩⁵

3. Re-evaluation of ascorbic acid (E 300), sodium ascorbate (E 301) and calcium ascorbate (E 302) as food additives — EFSA Journal 2015;13(12):4086. https://www.efsa.europa.eu/en/efsajournal/pub/4086 ↩ ↩²

4. Nitrosyl chloride — PubChem (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Nitrosyl-chloride ↩ ↩² ↩³

5. Safe and Suitable Ingredients Used in the Production of Meat, Poultry, and Egg Products (FSIS Directive 7120.1) — USDA FSIS. https://www.fsis.usda.gov/policy/fsis-directives/7120.1 ↩